My goal is to reduce our need on sfml_find_package until it can
finally be removed. It's preferred to simply use find_package to
find 3rd party projects.
I had to add IMPORTED targets to some of our find modules so that
we could get away from using INTERFACE libraries for external code.
That also implied that our find moduels need to be installed so that
users have access to them when processing SFML's config module.
Ported sfml-pi DRM/KMS backend written by @mickelson
Port co-authored by @substring
Co-authored-by: Andrew Mickelson <andrew.mickelson@gmail.com>
Co-authored-by: Gil Delescluse <frog2wah@gmail.com>
